linux-kernel - Re: Crypto test results unused?

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Message-ID: <m37hrn1a4k.fsf@intrepid.localdomain>
Date:	Tue, 12 Jan 2010 18:55:07 +0100
From:	Krzysztof Halasa <khc@...waw.pl>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: Crypto test results unused?

Herbert Xu <herbert@...dor.apana.org.au> writes:

>> On little-endian IXP4xx 3 hardware-assisted algorithms fail (due to
>> apparently unrelated bug which I will take care of). It seems the kernel
>> is still using these failing algorithms (my debugging code adds extra
>> fields to the /proc output):
>
> How did you determine that it was still being used? When a kernel
> user requests for an algorithm the system is supposed to skip
> anything which failed the self-test.

cat /proc/crypto shows "selftest: unknown" for those failed tests. I
don't know if that means it's used, but I'd expect "failed" or something
like that. Maybe it's simply a problem in /proc/crypto output.

> CRYPTO_ALG_DEAD is used to mark algorithms deleted from the
> system.  However, we don't delete algorithms just because they
> fail the self-test.  They remain in the system so you can come
> back and diagnose the problem.  They just aren't used by anyone.

Great.

Currently the /proc/crypto contains:

- for passed tests: "selftest: passed" (which is of course right)

- for failed tests: "selftest: unknown" (which is a surprise for me):

alg: skcipher: Test 1 failed on encryption for ecb(des)-ixp4xx
00000000: 01 23 45 67 89 ab cd e7

name         : ecb(des)
driver       : ecb(des)-ixp4xx
module       : ixp4xx_crypto
priority     : 300
refcnt       : 1
selftest     : unknown
type         : ablkcipher
async        : yes
blocksize    : 8
min keysize  : 8
max keysize  : 8
ivsize       : 0
geniv        : <default>

- for routines without a test: "selftest: passed" (which isn't true
  either)

alg: No test for authenc(hmac(md5),cbc(des)) (authenc(hmac(md5),cbc(des))-ixp4xx)

name         : authenc(hmac(md5),cbc(des))
driver       : authenc(hmac(md5),cbc(des))-ixp4xx
module       : ixp4xx_crypto
priority     : 300
refcnt       : 1
selftest     : passed
type         : aead
async        : yes
blocksize    : 8
ivsize       : 8
maxauthsize  : 16
geniv        : <built-in>

I think we need a way to differentiate between "really unknown" and
"failed", do we need another flag for it?
-- 
Krzysztof Halasa
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